Although published as an Early View article last month, our paper has now been published as part of the December issue of Ecology and Evolution - and our guppies made the front cover! See the previous blog post for more info.... |
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This post originally appeared on my research group's website.
Every year, the El Socorro Centre for Wildlife Conservation design and present an outreach exhibit at a science fair in Point Fortin, near the south-westerly tip of Trinidad. This year the theme was to be the wildlife of Matura, with an emphasis on the freshwater fish, so the Centre’s founder, Ricardo Meade, asked me to assist. I was more than happy to get involved, and while Ricardo and his team had the hard task of constructing tanks and catching fish, I set to work illustrating and researching the various species to compile a set of educational posters and labels to accompany the display. This wasn’t hard as most of the species were those that we commonly come across on our BioTIME surveys. Researchers at the University of St Andrews have made a shock discovery; that restricting a normally multiply mating fish to monogamous mating does not impair their colonisation ability. Their findings show that releasing just one or two fish into the wild may be enough to trigger an aquatic invasion. In a paper published this month in the journal BMC Ecology, researchers from the University of St Andrews tested whether forcing female guppies to be monogamous would impede their ability to establish viable populations. The guppy (Poecilia reticulata) is a successful invasive species throughout the tropics. In the wild it employs a 'multiple mating' strategy, and resulting broods commonly contain offspring sired by up to five different fathers. Previous studies have shown that mating with multiple partners carries a range of benefits, including increased genetic and phenotypic diversity of offspring, and inbreeding avoidance -which are potentially advantageous for a species attempting to colonise a new environment. However, as part of this latest study, female guppies were either allowed to mate with four males, or were restricted to one partner. Pregnant females were then left to establish populations in large tanks in the laboratory. After one year, the two treatments were compared. Dr Amy Deacon explains: "One of our key findings was that mating history did not predict establishment success, which was 88% in both treatments". What's more the researchers had expected that inbreeding depression might be evident in the behaviour of fish in the monogamous treatment, which would suggest that their ability to persist once established could be limited. However, this was not the case; newborn and adult male offspring of both treatments were equally good at avoiding predators and at courting females. These results suggest that even when denied the option of multiple mating, singly-mated female guppies can produce viable populations, at least at the founder stage. The ability to colonise even when multiple mating is restricted may prove to be critical during introductions, where a few individuals are released into enclosed water bodies before finding their way into natural ecosystems. For example, guppies are commonly introduced into rivers or ponds as unwanted pets, or into troughs or wells for mosquito control, but later tend to spread to new habitats during floods or monsoons. Once established in rivers and streams, aquatic invaders are notoriously difficult to eradicate. The findings of this study reinforce the message that although seemingly harmless, releasing just one or two individuals can lead to a potentially invasive population. The full text (open access) article can be viewed at: http://www.biomedcentral.com/1472-6785/14/18 Authored by me, this press released was edited and issued by the University of St Andrews Press Office. Coverage in the media includes: http://www.heraldscotland.com/news/home-news/scientists-discover-that-monogamy-does-not-curb-colonisation-by-guppies.24607524 http://phys.org/news/2014-06-invasion-monogamous-fish.html http://cryptozoologynews.blogspot.com/2014/06/invasion-of-monogamous-fish.html More than just guppies: Arima Valley’s freshwater fauna A report originally published in the TTFNC Quarterly Bulletin, by Amy Deacon and Ryan Mohammed. The picturesque freshwater streams of the Arima valley are internationally famous as the subject of hundreds of scientific papers about guppy behaviour and evolution. However, the Freshwater Group for the 2013 BioBlitz was more interested in the huge variety of species which share the habitat – from larger guppy-eating fish like the sardines (Characins), to the microscopic rock-bound diatoms on which guppies graze. Led by Amy Deacon, Ryan Mohammed and Erin Mangal, a full and enthusiastic team sampled seven sites all the way from Verdant Vale, including Simla, Temple Village and sites within the grounds of the AWNC itself. These sites included some deep pools as well as shallow riffles. Using two-person hand seine nets we recorded a total of six species of fish, including the spectacular zangee (Synbranchus marmoratus) and an unusually large sardine (Astyanax bimaculatus). Fish pots were also used overnight with limited success due to the shallow depth of the river, but nonetheless yielded Trinidad’s two species of teta – ‘normal’, and ‘jumbie’ or ‘doctor’ teta (Hypostomus robini and Ancistrus maracasae). Despite doubling the total of last year’s Tucker valley snapshot, six species is certainly an underestimate of what are actually there. Notable absences included the cichlids, Crenicichla sp. and Andinoacara pulcher. Thanks to help from afar from Odonata expert John Michalski in the form of an illustrated list, we were able to identify several species of dragonflies and damselflies relatively easily – some of the prettiest were spotted at the Simla cement ponds, including the beautiful turquoise Micrathyria atra. Our efforts to sample Odonata extended to capturing some of the aquatic larvae as well, using a surber sampler. This piece of equipment also allowed us to catch and identify the larval stages of mayflies, caddisflies, stoneflies and various other bottom-dwelling macroinvertebrates. One crustacean species was confirmed - the manicou crab (Eudaniela garmani) and several aquatic gastropods including Pomacea glauca and Marisa cornuarietis. Back at base camp on Sunday morning, children enjoyed taking part in our ‘colour in the guppy’ competition, and visitors could view fish in the display tanks. There were also some wriggling aquatic invertebrates to look at under the microscope and posters all about some of the streams’ smallest inhabitants - the diatoms. These are tiny photosynthetic creatures encased in intricate glass shells and are normally invisible to the naked eye. However, under the microscope it is possible to admire their beauty and diversity at close range. We identified at least six different species of diatoms in the Arima Valley waterways. Once again, the Freshwater Group have revealed hidden secrets of Trinidad’s streams, opening peoples’ eyes to the weird and wonderful creatures that grow, swim and crawl alongside the fish… This article originally appeared on the BioTIME website. Earlier this year, I was invited to give a lecture at the monthly meeting of the Trinidad and Tobago Field Naturalists’ Club. This excellent organisation was founded in 1891, and organises weekly hikes and specialist field trips for its members, who encompass a wide range of ages and backgrounds, united by an interest in Trinidad’s abundant and unique natural history. Alongside steel pan, calypso and rum, the guppy (Poecilia reticulata) is one of Trinidad and Tobago’s most famous exports – and, like carnival, birdlife and leatherback turtles, it is also one its most popular attractions, drawing in many international academics each year. However, despite being one of the most-studied fish in the world, surprisingly it tends to be dismissed as a lowly ‘drain fish’ in its native land, due to its great abundance and ability to survive in less-than-pristine habitats. I was delighted to take the opportunity to speak about our research into the remarkable reproductive ability of the guppy, and how this has allowed it to colonise habitats all over the globe, as well as discussing more generally why this species has been so keenly studied. Many in the audience appeared to be genuinely unaware of how fascinating this seemingly insignificant little fish is, and how important it has been to our knowledge of evolution and ecology, and were extremely interested to hear about it. The level of interest in the topic was confirmed by the deluge of insightful and pertinent questions at the end of the lecture, which touched upon many of the important areas of current research into Trinidad’s most famous fish. I am hopeful that with greater awareness of the importance of this species to science among the inhabitants of Trinidad and Tobago, we will both start to see more Trinidadians joining the international guppy research community, and also notice an increased public awareness of the urgent need for conservation of the guppy’s Northern Range habitat, which faces constant threat from agriculture, pollution and, most worryingly, expanding quarrying operations. During a BioBlitz, scientists, naturalists and volunteers take part in a 24hr period of intense surveying of a particular area with the aim of estimating the number of species present, while educating and enthusing the public about their local biodiversity. One weekend in November 2012, led by Mike Rutherford of the University of the West Indies Zoology museum, we set up a BioBlitz base camp in Trinidad’s Tucker Valley, in the North-West of the island. The valley comprises of a variety of terrestrial and aquatic habitats, and volunteers were divided into groups according to their interests and expertise. As well as designing the event logo, I helped organise the Freshwater Group, which included Raj Mahabir, Dawn Phillip and several other scientists and helpers. We began on the Saturday by surveying several sites along the Cuesa river, ranging from small forest streams to the mangrove-dominated estuary area, and recorded every species we came across – from diatoms to spectacled caiman! Many specimens were identifiable to species level in the field, but others were brought back to base camp to be examined more closely with the help of microscopes and a library of taxonomic literature. On Sunday, emphasis shifted from science to outreach, and the base camp was opened to the public, who could watch the scientists at work, and also see a variety of animals in containers and glass tanks. The more adventurous were taken on spotters walks to see the biodiversity first hand! I led a group of 30 adults and children on a river walk to show them that it’s not only fish that live in and around streams and rivers – we found over 40 species, and everyone had a go at using a dip net or surber sampler to catch guppies or sample aquatic invertebrates. In total, we recorded nearly 700 species, and there are now plans to make Trinidad’s BioBlitz an annual event! More details can be found in the local press coverage: Originally posted on the Biodiversity & Behaviour Research Group website. Largely ignored as a lowly ‘drain fish’ in its native land, many Trinidadians are surprised to discover that the common guppy forms the basis of entire careers for hundreds of international biologists. However, as ‘the home of the guppy’, Trinidad provided the ideal venue for the 5th International Conference of Poeciliid Biologists, which took place at The University of the West Indies in June 2012. This conference was chaired by Professor Indar Ramnarine and co-chaired by Dr Amy Deacon of the Behaviour and Biodiversity Research Group with additional help from former BBRG member Dr Dawn Phillip and BioTIME assistant Raj Mahabir. Academics from throughout the world were brought together on this beautiful island to share their passion for all aspects of the biology of poeciliid fish. The Behaviour and Biodiversity Research group was well-represented, with the attendance of many past and present members. Amy described her work on the invasive spread and colonisation ability of the guppy, Mora spoke about behavioural responses to novel environments in guppies, Al explained how guppies acclimate to different thermal regimes and Alfredo presented his work on transgenerational effects of fatty acid nutrition in mosquitofish. BBRG’s own Anne Magurran was one of three keynote speakers. She opened the first session with an historical overview of guppy science in Trinidad, beginning with its supposed ‘discovery’ by Robert John Lechmere Guppy in 1866 and the subsequent use of the Northern Range as a natural laboratory which continues into the present day. The second keynote speaker was another frequent visitor to Trinidad, Professor David Reznick of the University of California, Riverside, who theorised about the origin of the poeciliid ability to give birth to live young, offering a fascinating evolutionary genetics perspective. On the final day, the audience was wowed by Professor Jens Krause of Humboldt University in Berlin, and his use of guppies and robotic fish to explain swarm behaviour and intelligence in a whole range of species – including humans. The conference concluded with a series of exciting fieldtrips designed to give delegates a true taste of Trinidad – including leatherback turtle watching, a trip to the world famous Asa Wright Nature Centre and an afternoon swim at the beach, followed by the Trinidadian version of fish and chips – ‘bake and shark’ (although being ecologically responsible fish biologists, bake and kingfish was the preferred choice!) Finally, delegates enjoyed a spectacular hike up the Turure river, which ended at a series of beautiful waterfalls… It was a real treat to snorkel with wild guppies in the pools, watching the famous courtship behaviours that many of the visiting academics had only ever seen in laboratory fish tanks. The 6th International Conference of Poeciliid Biologists will take place in 2014, and will be chaired by Dr Darren Croft and Dr Safi Darden at the University of Exeter. I co-wrote this press release for the paper 'How reproductive ecology contributes to the spread of a globally invasive fish' published in the journal PLoS one: Think twice before setting free unwanted pet fish, say scientists. The release of a single female guppy into the wild can generate entire new populations, even with no males present, according to new research. New research by biologists at the University of St Andrews and the University of the West Indies on this popular ornamental species, reveals how its ability to keep on reproducing has earned the guppy its reputation as one of the world’s most invasive fish. The study, published today (Monday 19th September 2011), reports that the apparently harmless release of guppies into the wild has led to the fish being found in every continent with the exception of Antarctica. The guppy, whose native home is Trinidad and the north-eastern fringe of South America, is now present in over 70 countries worldwide. Since a single female guppy can establish a viable new population, the research demonstrates that even well-intentioned releases of discarded pets can contribute to the loss of biological diversity. St Andrews lead researcher Dr Amy Deacon commented, “Our findings show that the range of the guppy has expanded dramatically since the early 1900s”. The scientists began by surveying hundreds of fish biologists around the world. Responses confirmed that the two most important routes of guppies finding their way into the wild are the escapes of ornamental fish, and deliberate introductions designed to control the larvae of mosquitoes that spread malaria. In places such as Southern India, guppies are routinely released into water troughs, wells and small ponds for mosquito control. Although self-contained at first, heavy rains and flooding mean that the fish eventually find their way to streams and rivers where they come into contact with native fish. Dr Deacon continued, “Usually only one or a few fish are released. We know that the vast majority of species introduced to a new habitat in this way are unable to survive, let alone establish a population, which left us with a huge question mark.” To try to solve this mystery, the researchers conducted a simple experiment, in which single wild female guppies were placed into outdoor tanks. After two years, they discovered that almost all of the tanks contained populations of guppies, each founded by just one female. Dr Deacon explained how this finding might explain their success as an invasive species, “Sperm storage is an excellent adaptation for living in constantly changing habitats, and it might also explain the guppies’ global success. Female guppies can store sperm in their reproductive tracts for many months after mating, and this enables single fish to establish populations, even when no males are present. “We also found that these populations kept all of the important behaviours that wild guppies have, so they would be well-equipped for surviving in a new environment.” Dr Deacon continued, “Our study shows why we should be cautious when releasing exotic species. “Seemingly harmless activities such as a child freeing a few pet fish or a concerned householder using guppies to control mosquitoes, can ultimately contribute to the reduction of biodiversity in freshwater habitats across the world.” The research, published by the journal PLoS ONE, was funded by the Natural Environment Research Council and the European Research Council. This press release led to several features in the print and online media, including: http://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-14972053 http://www.dailymail.co.uk/sciencetech/article-2039857/A-brood-apart-Household-pet-fish-favourites-turn-tropical-terrors-released-wild.html http://news.stv.tv/tayside/270928-plenty-of-fish-effect-down-to-single-wild-females-say-scientists/ http://www.advancedaquarist.com/blog/a-solitary-female-guppy http://www.practicalfishkeeping.co.uk/content.php?sid=4324 http://www.neatorama.com/2011/09/22/one-female-guppy-is-enough-to-invade-an-ecosystem/ |
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